linux/fs/ecryptfs/file.c
Jeff Mahoney f0fe970df3 ecryptfs: don't allow mmap when the lower fs doesn't support it
There are legitimate reasons to disallow mmap on certain files, notably
in sysfs or procfs.  We shouldn't emulate mmap support on file systems
that don't offer support natively.

CVE-2016-1583

Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Cc: stable@vger.kernel.org
[tyhicks: clean up f_op check by using ecryptfs_file_to_lower()]
Signed-off-by: Tyler Hicks <tyhicks@canonical.com>
2016-07-08 10:35:28 -05:00

427 lines
12 KiB
C

/**
* eCryptfs: Linux filesystem encryption layer
*
* Copyright (C) 1997-2004 Erez Zadok
* Copyright (C) 2001-2004 Stony Brook University
* Copyright (C) 2004-2007 International Business Machines Corp.
* Author(s): Michael A. Halcrow <mhalcrow@us.ibm.com>
* Michael C. Thompson <mcthomps@us.ibm.com>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation; either version 2 of the
* License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
* 02111-1307, USA.
*/
#include <linux/file.h>
#include <linux/poll.h>
#include <linux/slab.h>
#include <linux/mount.h>
#include <linux/pagemap.h>
#include <linux/security.h>
#include <linux/compat.h>
#include <linux/fs_stack.h>
#include "ecryptfs_kernel.h"
/**
* ecryptfs_read_update_atime
*
* generic_file_read updates the atime of upper layer inode. But, it
* doesn't give us a chance to update the atime of the lower layer
* inode. This function is a wrapper to generic_file_read. It
* updates the atime of the lower level inode if generic_file_read
* returns without any errors. This is to be used only for file reads.
* The function to be used for directory reads is ecryptfs_read.
*/
static ssize_t ecryptfs_read_update_atime(struct kiocb *iocb,
struct iov_iter *to)
{
ssize_t rc;
struct path *path;
struct file *file = iocb->ki_filp;
rc = generic_file_read_iter(iocb, to);
if (rc >= 0) {
path = ecryptfs_dentry_to_lower_path(file->f_path.dentry);
touch_atime(path);
}
return rc;
}
struct ecryptfs_getdents_callback {
struct dir_context ctx;
struct dir_context *caller;
struct super_block *sb;
int filldir_called;
int entries_written;
};
/* Inspired by generic filldir in fs/readdir.c */
static int
ecryptfs_filldir(struct dir_context *ctx, const char *lower_name,
int lower_namelen, loff_t offset, u64 ino, unsigned int d_type)
{
struct ecryptfs_getdents_callback *buf =
container_of(ctx, struct ecryptfs_getdents_callback, ctx);
size_t name_size;
char *name;
int rc;
buf->filldir_called++;
rc = ecryptfs_decode_and_decrypt_filename(&name, &name_size,
buf->sb, lower_name,
lower_namelen);
if (rc) {
printk(KERN_ERR "%s: Error attempting to decode and decrypt "
"filename [%s]; rc = [%d]\n", __func__, lower_name,
rc);
goto out;
}
buf->caller->pos = buf->ctx.pos;
rc = !dir_emit(buf->caller, name, name_size, ino, d_type);
kfree(name);
if (!rc)
buf->entries_written++;
out:
return rc;
}
/**
* ecryptfs_readdir
* @file: The eCryptfs directory file
* @ctx: The actor to feed the entries to
*/
static int ecryptfs_readdir(struct file *file, struct dir_context *ctx)
{
int rc;
struct file *lower_file;
struct inode *inode = file_inode(file);
struct ecryptfs_getdents_callback buf = {
.ctx.actor = ecryptfs_filldir,
.caller = ctx,
.sb = inode->i_sb,
};
lower_file = ecryptfs_file_to_lower(file);
rc = iterate_dir(lower_file, &buf.ctx);
ctx->pos = buf.ctx.pos;
if (rc < 0)
goto out;
if (buf.filldir_called && !buf.entries_written)
goto out;
if (rc >= 0)
fsstack_copy_attr_atime(inode,
file_inode(lower_file));
out:
return rc;
}
struct kmem_cache *ecryptfs_file_info_cache;
static int read_or_initialize_metadata(struct dentry *dentry)
{
struct inode *inode = d_inode(dentry);
struct ecryptfs_mount_crypt_stat *mount_crypt_stat;
struct ecryptfs_crypt_stat *crypt_stat;
int rc;
crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat;
mount_crypt_stat = &ecryptfs_superblock_to_private(
inode->i_sb)->mount_crypt_stat;
mutex_lock(&crypt_stat->cs_mutex);
if (crypt_stat->flags & ECRYPTFS_POLICY_APPLIED &&
crypt_stat->flags & ECRYPTFS_KEY_VALID) {
rc = 0;
goto out;
}
rc = ecryptfs_read_metadata(dentry);
if (!rc)
goto out;
if (mount_crypt_stat->flags & ECRYPTFS_PLAINTEXT_PASSTHROUGH_ENABLED) {
crypt_stat->flags &= ~(ECRYPTFS_I_SIZE_INITIALIZED
| ECRYPTFS_ENCRYPTED);
rc = 0;
goto out;
}
if (!(mount_crypt_stat->flags & ECRYPTFS_XATTR_METADATA_ENABLED) &&
!i_size_read(ecryptfs_inode_to_lower(inode))) {
rc = ecryptfs_initialize_file(dentry, inode);
if (!rc)
goto out;
}
rc = -EIO;
out:
mutex_unlock(&crypt_stat->cs_mutex);
return rc;
}
static int ecryptfs_mmap(struct file *file, struct vm_area_struct *vma)
{
struct file *lower_file = ecryptfs_file_to_lower(file);
/*
* Don't allow mmap on top of file systems that don't support it
* natively. If FILESYSTEM_MAX_STACK_DEPTH > 2 or ecryptfs
* allows recursive mounting, this will need to be extended.
*/
if (!lower_file->f_op->mmap)
return -ENODEV;
return generic_file_mmap(file, vma);
}
/**
* ecryptfs_open
* @inode: inode specifying file to open
* @file: Structure to return filled in
*
* Opens the file specified by inode.
*
* Returns zero on success; non-zero otherwise
*/
static int ecryptfs_open(struct inode *inode, struct file *file)
{
int rc = 0;
struct ecryptfs_crypt_stat *crypt_stat = NULL;
struct dentry *ecryptfs_dentry = file->f_path.dentry;
/* Private value of ecryptfs_dentry allocated in
* ecryptfs_lookup() */
struct ecryptfs_file_info *file_info;
/* Released in ecryptfs_release or end of function if failure */
file_info = kmem_cache_zalloc(ecryptfs_file_info_cache, GFP_KERNEL);
ecryptfs_set_file_private(file, file_info);
if (!file_info) {
ecryptfs_printk(KERN_ERR,
"Error attempting to allocate memory\n");
rc = -ENOMEM;
goto out;
}
crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat;
mutex_lock(&crypt_stat->cs_mutex);
if (!(crypt_stat->flags & ECRYPTFS_POLICY_APPLIED)) {
ecryptfs_printk(KERN_DEBUG, "Setting flags for stat...\n");
/* Policy code enabled in future release */
crypt_stat->flags |= (ECRYPTFS_POLICY_APPLIED
| ECRYPTFS_ENCRYPTED);
}
mutex_unlock(&crypt_stat->cs_mutex);
rc = ecryptfs_get_lower_file(ecryptfs_dentry, inode);
if (rc) {
printk(KERN_ERR "%s: Error attempting to initialize "
"the lower file for the dentry with name "
"[%pd]; rc = [%d]\n", __func__,
ecryptfs_dentry, rc);
goto out_free;
}
if ((ecryptfs_inode_to_private(inode)->lower_file->f_flags & O_ACCMODE)
== O_RDONLY && (file->f_flags & O_ACCMODE) != O_RDONLY) {
rc = -EPERM;
printk(KERN_WARNING "%s: Lower file is RO; eCryptfs "
"file must hence be opened RO\n", __func__);
goto out_put;
}
ecryptfs_set_file_lower(
file, ecryptfs_inode_to_private(inode)->lower_file);
rc = read_or_initialize_metadata(ecryptfs_dentry);
if (rc)
goto out_put;
ecryptfs_printk(KERN_DEBUG, "inode w/ addr = [0x%p], i_ino = "
"[0x%.16lx] size: [0x%.16llx]\n", inode, inode->i_ino,
(unsigned long long)i_size_read(inode));
goto out;
out_put:
ecryptfs_put_lower_file(inode);
out_free:
kmem_cache_free(ecryptfs_file_info_cache,
ecryptfs_file_to_private(file));
out:
return rc;
}
/**
* ecryptfs_dir_open
* @inode: inode specifying file to open
* @file: Structure to return filled in
*
* Opens the file specified by inode.
*
* Returns zero on success; non-zero otherwise
*/
static int ecryptfs_dir_open(struct inode *inode, struct file *file)
{
struct dentry *ecryptfs_dentry = file->f_path.dentry;
/* Private value of ecryptfs_dentry allocated in
* ecryptfs_lookup() */
struct ecryptfs_file_info *file_info;
struct file *lower_file;
/* Released in ecryptfs_release or end of function if failure */
file_info = kmem_cache_zalloc(ecryptfs_file_info_cache, GFP_KERNEL);
ecryptfs_set_file_private(file, file_info);
if (unlikely(!file_info)) {
ecryptfs_printk(KERN_ERR,
"Error attempting to allocate memory\n");
return -ENOMEM;
}
lower_file = dentry_open(ecryptfs_dentry_to_lower_path(ecryptfs_dentry),
file->f_flags, current_cred());
if (IS_ERR(lower_file)) {
printk(KERN_ERR "%s: Error attempting to initialize "
"the lower file for the dentry with name "
"[%pd]; rc = [%ld]\n", __func__,
ecryptfs_dentry, PTR_ERR(lower_file));
kmem_cache_free(ecryptfs_file_info_cache, file_info);
return PTR_ERR(lower_file);
}
ecryptfs_set_file_lower(file, lower_file);
return 0;
}
static int ecryptfs_flush(struct file *file, fl_owner_t td)
{
struct file *lower_file = ecryptfs_file_to_lower(file);
if (lower_file->f_op->flush) {
filemap_write_and_wait(file->f_mapping);
return lower_file->f_op->flush(lower_file, td);
}
return 0;
}
static int ecryptfs_release(struct inode *inode, struct file *file)
{
ecryptfs_put_lower_file(inode);
kmem_cache_free(ecryptfs_file_info_cache,
ecryptfs_file_to_private(file));
return 0;
}
static int ecryptfs_dir_release(struct inode *inode, struct file *file)
{
fput(ecryptfs_file_to_lower(file));
kmem_cache_free(ecryptfs_file_info_cache,
ecryptfs_file_to_private(file));
return 0;
}
static loff_t ecryptfs_dir_llseek(struct file *file, loff_t offset, int whence)
{
return vfs_llseek(ecryptfs_file_to_lower(file), offset, whence);
}
static int
ecryptfs_fsync(struct file *file, loff_t start, loff_t end, int datasync)
{
int rc;
rc = filemap_write_and_wait(file->f_mapping);
if (rc)
return rc;
return vfs_fsync(ecryptfs_file_to_lower(file), datasync);
}
static int ecryptfs_fasync(int fd, struct file *file, int flag)
{
int rc = 0;
struct file *lower_file = NULL;
lower_file = ecryptfs_file_to_lower(file);
if (lower_file->f_op->fasync)
rc = lower_file->f_op->fasync(fd, lower_file, flag);
return rc;
}
static long
ecryptfs_unlocked_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
struct file *lower_file = ecryptfs_file_to_lower(file);
long rc = -ENOTTY;
if (!lower_file->f_op->unlocked_ioctl)
return rc;
switch (cmd) {
case FITRIM:
case FS_IOC_GETFLAGS:
case FS_IOC_SETFLAGS:
case FS_IOC_GETVERSION:
case FS_IOC_SETVERSION:
rc = lower_file->f_op->unlocked_ioctl(lower_file, cmd, arg);
fsstack_copy_attr_all(file_inode(file), file_inode(lower_file));
return rc;
default:
return rc;
}
}
#ifdef CONFIG_COMPAT
static long
ecryptfs_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
struct file *lower_file = ecryptfs_file_to_lower(file);
long rc = -ENOIOCTLCMD;
if (!lower_file->f_op->compat_ioctl)
return rc;
switch (cmd) {
case FS_IOC32_GETFLAGS:
case FS_IOC32_SETFLAGS:
case FS_IOC32_GETVERSION:
case FS_IOC32_SETVERSION:
rc = lower_file->f_op->compat_ioctl(lower_file, cmd, arg);
fsstack_copy_attr_all(file_inode(file), file_inode(lower_file));
return rc;
default:
return rc;
}
}
#endif
const struct file_operations ecryptfs_dir_fops = {
.iterate_shared = ecryptfs_readdir,
.read = generic_read_dir,
.unlocked_ioctl = ecryptfs_unlocked_ioctl,
#ifdef CONFIG_COMPAT
.compat_ioctl = ecryptfs_compat_ioctl,
#endif
.open = ecryptfs_dir_open,
.release = ecryptfs_dir_release,
.fsync = ecryptfs_fsync,
.llseek = ecryptfs_dir_llseek,
};
const struct file_operations ecryptfs_main_fops = {
.llseek = generic_file_llseek,
.read_iter = ecryptfs_read_update_atime,
.write_iter = generic_file_write_iter,
.unlocked_ioctl = ecryptfs_unlocked_ioctl,
#ifdef CONFIG_COMPAT
.compat_ioctl = ecryptfs_compat_ioctl,
#endif
.mmap = ecryptfs_mmap,
.open = ecryptfs_open,
.flush = ecryptfs_flush,
.release = ecryptfs_release,
.fsync = ecryptfs_fsync,
.fasync = ecryptfs_fasync,
.splice_read = generic_file_splice_read,
};